Iranian Journal of Crop Sciences
Year:2002 | Volume:4 | Issue:4|Papers Count:9

In order to study effects of plant density on water use efficiency (WUE) in spring and summer growing seasons in Esfahan region, five safflower genotypes including two selected lines from Esfahan landraces and three improved cultivars (Arak 2811, Gilla and Kooseh) were compared in two growing season (sown on April. 4 and July. 6) and three plant densities (40, 20 and 13 plants per m2) using split-split plots experimental design in Isfahan in 2000. The results showed that differences in water use efficiency between two growing season was significant (P<0.01). Water use efficiency in summer growing season better than spring growing season by 17%. Summer growing season produced 474.6 kg/ha less grain yield than spring growing season. however, WUE in summer growing season was higher than spring growing season. Plant density effects were also significant on water use efficiency. The highest and the lowest of WUE were 0.481 kg/m3 and 0.308 kg/m3 40 and 13 plants per m2, respectively. The main factor that contributed to higher WUE was higher plant in density which increased grain yield. Arak 2811 in spring growing season and line 1 in summer growing season had the highest WUE.

In order to determine effects of weed competition on canopy architecture of wheat, an experiment was conducted in Mashhad, 2001 and 2002. The treatments included three Crucifer’s family weeds (Wild mustard. Turnip weed and Flix weed) and five levels of weed density (control, 4, 8, 16 and 32 plants/m2 for wild mustard and turnip weed, and control, 16,32,64 and 128 plantlm2 for Flix weed). Randomized complete block design with four replications in an additive series technique was employed as the experimental design. An ANOVA procedure indicated significant effects of wild mustard and turnip weed on plant height, leaf area and leaf distribution of wheat. Increasing weed plant density, reduced the height and leaf area of wheat. In addition, in comparison with control, leaf area of wheat was more distributed in the upper part of the canopy. As plant density of weeds increased, their plant height also increased and more leaf area was measured in the upper part of weeds conopy.

Lilium ledebourii Boiss is a native flower in the north of Iran, however it is an endangered species. In order to introduce and domesticate endemic plants, the first step is evaluation for propagation. One of the best and most propagation vegetative method of Lilies is in vitro scale culture using plant growth regulators in different condition. This experiment conducted using a completely randomized design  (CRC) with four factors. 1- Light period at two levels:A: Lightness (16 hr light and 8 hr dark) B: darkness (24 hr dark). 2- Regional explant at two levels: A: Half distal scale, B: Half basal scale. 3-Concentrations of 6-benzylamynopurine (BAP) at three levels A: Zero or control B:0.01 mgl-1 C:0.1 mgl-1 4- Concentrations of α-naphtalen acetic acid (NAA) at four level A: Zero B: 0.01 mgl-1 C:0.05 mgl-1 D:0.1 mgl-1 Analysis of variance was performed on the collected data, and mean comparison was carried out, using Duncan’s multiple range test (p<0.05). Results showed that light period increased the total weight, number of bulblets and regeneration percentage, whereas darkness treatment increased weight of bulblets and rooting percentage. Number and weight of bulblets, regeneration percentage and number of roots was better when explant obtained from basal scale. Different concentration of BAP had significant effect on some traits. The highest number of bulblets, rooting and regeneration percentage obtained in control treatment and the greatest weight of bulblets obtained by 0.1 mgl-1 BAP and the highest number of roots obtained in control and 0.01 mgl-1 BAP.Different concentration of NAA had also significant effects on some traits. The greatest total weight and number of bulblets obtained by 0.1 mgl-1 NAA and the weight of bulblets increased in all of the NAA concentrations. Concentrations of 0.05 and 0.1 mgl-1 NAA increased number of roots and rooting percentage.

In order to study the effect of terminal heat stress on some quantitative traits and tolerance of five hull-less barley genotypes, an experiment was carried out at the Gachsaran, Iran, on a silty clay loam soil, using a split plot experimental design with three replications. Four sowing dates (Dec. 6 and Dec. 21 in 2000, and Jan. 5 and Jan. 20 in 2001) were assigned to main plots and five hull-less barley genotypes (FICC0963, FICCI570. FICC 1571, FICC 1725 and FICC 2712) to subplots. Results indicated that delay in sowing date decreased dry matter (16%), plant height (19%), grain yield (23%), harvest index (9%), number of days to flowering (11%) and number of days to physiological maturity (16%). Grain yield reduction was due mainly to reduced spike number per m2 (12%), 1000 grain weight (16%) and duration of grain filling (30%). Genotypes showed different responses to terminal heat stress and the highest grain yield was obtained from FICC0963. Considering the stress tolerance index (STI), FICC 0963 had the highest grain yield under the optimum condition (4285 kg / ha) as well as under terminal heat stress condition (3361 kg / ha). It also performed to be resistant to terminal heat stress conditions, according to stress susceptibility index (SSI).

A Field experiment was conducted in order to investigate effects of weeding,Trifluralin (pre-sowing herbicide), Haloxyfop ethoxyethyl, Bentazon, Sethmoxdim (post-emergenc herbicides) and a combination of these treatments on weed control in common bean. The experiment was carried out in 2000-2001 using RCBD with 10 treatments and 4 replications at the Azad University of Shahr-e-Rey experimental field station. Results showed that highest yield (581.1 g/m2) was achived from Trifluralin + twice weeding treatment followed by. twice weeding (527.6 g/m2). Maximum yield (466.4 g/m2) from post emergence herbicides group was obtained from Trifluralin + Haloxyfop ethoxyethyl treatment. Treatments in which weeding was included were the best.This finding signifies the importance of weeding in common bean crop production. Results of this experiment indicate that sole application of pre-sowing herbicide (Trifluralin) for weed control in common bean is noteffective. However, in order to control weeds in common bean we suggest application of Trifluralin together with twice hand weeding. Hand weeding in small fields with cheap workers is economically acceptable. Otherwise, a combination of Trifluralin (pre-sowing herbicide) and Haloxyfop ethoxyethyl (post-emergence herbicide) should be applied.

In order to evaluate the variation in wheat leaf total free phenol, total free amino acids, free proline and total protein in reaction to Russian aphid, an experiment was carried out on 7 bread wheat genotypes (with different levels of resistance). The experiment was performed in greenhouse conditions at Shiraz 1999. The results indicated that Russian aphid caused stress on all genotypes and total free phenol increased in all of them. High level of resistance in genotypes was correlated with free proline content before contamination (r=0.87, p<0.0l). In resistant genotypes free proline accumulated rapidly after contamination. The results also signified that toxicity index value (ratio of total free phenol to total free amino acids) was correlated with resistance of plant to Russian aphid (r=0.73, p<0.05), therefore, resistant genotypes had higher values. According to the results, total protein of resistant genotypes was also higher than susceptible genotypes. On the other hand, contamination caused reduction in total protein content in all genotypes.

This study was conducted during 1997 and 1998 at agricultural research centers of Mashad, Dezful, Moghan and Karaj to reduce herbicide usage and protecting environment through application of Triflusulfuron with broad spectrum of weed control low residual and low application rates at the early growth stages of weeds and sugarbeet crop. The experimental design was a randomized complete blocks with 11 treatments in four replications. Herbicide treatments included post emergence applications of Triflusulfuron at 15 and 20 g a.i./ha at the cotyledonous stage of sugarbeet crop. Sequential applications of Triflusulfuron at 10 and 15 g a.i./ha at the cotyledonous stage of sugarbeet crops, Triflusulfuron + Phenmedipham at 15 g a.i./ha + 0.3kg a.i./ha, Choridazon + Phenmedipham at (1.6 + 0.3) kg a.i./ha, Phenmedipham at 0.3 kg a.i./ha at the cotyledonous stage of sugarbeet. Phenmedipham at 0.78 kg a.i./ha and Chloridazon at 4 kg a.i./ha at four leaf stage of sugarbeet crop, weed free and weedy controls. Effect of herbicide treatments on weed control and sugarbeet root yield were significantly different. Application of the mixture of Triflusulfuron + Phenmedipham at (15g+0.3kg) ai/ha had the highest level of weed control as compared to the weedy check and controlled broadleaved weeds by 78%. Weed free control and application of Triflusulfuron + Phenmedipham treatments with 45.13 and 36.94 t/ha produced the highest yield of sugarbeet root, respectively. However, weedy control with 10.53 t/ha had the lowest sugarbeet root yield.